Which of the following represents the number of patients needed to treat to save 1 life with addition of beta-blockers?
A. 1 / (0.40 – 0.34) (Correct)
B. 1 / (0.34 – 0.40)
C. 1 / (40 – 34)
D. 1 / (34 – 40)
E. 1 / 0.83
C and D. FALSE: These calculations inadvertently utilize the integral numbers (not percentages) for calculating risk in both study arms. E. FALSE: This calculation is the inverse of the hazard ratio, which is unrelated to the NNT.
Reference: 1. Le T, Bhushan V, Skelley N. First Aid for the USMLE Step 2CK, 8th ed. New York, NY: McGraw-Hill. 2012. 2. Poole-Wilson PA, et al. Comparison of carvedilol and metoprolol on clinical outcomes in patients with chronic heart failure in the Carvedilol Or Metoprolol European Trial (COMET): randomised controlled trial. Lancet. 2003 Jul 5;362(9377):7-13.
USMLE Step 3
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